GoStudy/Map/main.go

package main

import (
	"fmt"
	"math/rand"
	"sort"
)

func main() {
	myMap := make(map[string]int)
	myMap["song"] = 1
	myMap["zhang"] = 2
	fmt.Println(myMap)

	myMap2 := map[string]string{
		"123": "123",
		"456": "456",
	}
	fmt.Println(myMap2)

	key, value := IsExist()
	if value {
		fmt.Printf("%v\n", key)
	} else {
		fmt.Printf("查无此人: %v\n", key)
	}
	RangeMap()

	DeleteKey("003")

	RangeMap2()

	MapSlice()

	SliceMap()
}

// IsExist 键是否存在
func IsExist() (int, bool) {
	fmt.Println("===IsExist===")
	mMap := make(map[string]int) //map类型的变量默认初始值为nil，需要使用make()函数来分配内存
	mMap["张三"] = 333
	mMap["李四"] = 444
	v, ok := mMap["张三"]
	return v, ok
}

// RangeMap 遍历
func RangeMap() {
	fmt.Println("===RangeMap===")
	rMap := map[string]string{
		"001": "张三",
		"002": "李四",
		"003": "王五",
		"004": "周六",
	}
	for k, v := range rMap {
		fmt.Println(k, v)
	}
	fmt.Println("range key")

	for rk := range rMap {
		fmt.Println(rk)
	}
}

// DeleteKey 删除键
func DeleteKey(key string) {
	fmt.Println("===DeleteMap===")
	dMap := map[string]string{
		"001": "张三",
		"002": "李四",
		"003": "王五",
		"004": "周六",
	}
	delete(dMap, key)
	for k, v := range dMap {
		fmt.Println(k, v)
	}
}

// RangeMap2 指定顺序遍历
func RangeMap2() {
	fmt.Println("===RangeMap2===")
	scoreMap := make(map[string]int, 200)

	for i := 0; i < 20; i++ {
		key := fmt.Sprintf("stu%02d", i)
		value := rand.Intn(100)
		scoreMap[key] = value
	}
	//fmt.Println(scoreMap)
	//将key存入切片
	keys := make([]string, 0, 200)
	fmt.Println("排序前")
	for key := range scoreMap {
		keys = append(keys, key)
		fmt.Printf("%v: %v ", key, scoreMap[key])
	}

	sort.Strings(keys)

	fmt.Println("\n排序后")
	//for i := 0; i < len(keys); i++ {
	//	fmt.Printf("%v ", scoreMap[keys[i]])
	//}

	for _, key := range keys {
		fmt.Printf("%v: %v ", key, scoreMap[key])
	}
	fmt.Println()
}

// MapSlice 元素为map类型的切片
func MapSlice() {
	fmt.Println("===元素为map类型的切片===")
	//先申明并初始化一个map“切片”
	mapSlice := make([]map[string]string, 3)
	for index, value := range mapSlice {
		fmt.Printf("index: %v, value: %v\n", index, value)
	}
	//在对切片中的map进行初始化
	mapSlice[0] = make(map[string]string, 10)
	mapSlice[0]["name"] = "swansong"
	mapSlice[0]["age"] = "22"
	mapSlice[0]["sex"] = "man"

	for index, value := range mapSlice {
		fmt.Printf("index: %v, value:%v\n", index, value)
	}
}

// SliceMap 值为切片类型的map
func SliceMap() {
	fmt.Println("===值为切片的map===")
	sliceMap := make(map[string][]string, 3)
	//for index, value := range sliceMap {
	//	fmt.Printf("index: %v, value: %v", index, value)
	//}
	fmt.Println(sliceMap)
	key := "中国"
	value, ok := sliceMap[key]
	if !ok {
		value = make([]string, 0, 2)
	}
	value = append(value, "北京", "上海")
	sliceMap[key] = value
	fmt.Println(sliceMap)
}